Shipping regulations. >20Wh can't go by airpost in the west.
replyOppo doesn't have that issue in EU and ships 7500mah just fine though. Some also split batteries into two just to accommodate this.
replyThey split it up into multiple smaller cells to do that. Or don't ship by airmail.
replySplit batteries are also better for efficient space usage (depending on the chassis) and longevity.
replyIs this enforced?
replyBecause those are a different kind of battery, silicon-carbon and they wear out much quicker. I am sure they will eventually though.
replyMight be longevity concerns. Those new batteries are impressive, but the concern is that they will degrade a lot.
replyAlso, remember the exploding Samsung phone. Experiments with batteries are risky for those companies.